AMOKG SIMPLE SAECODE OEGANISMS. 



393 



tate to regard tbetn as tlie proper brood of the Arcella, and com- 

 pares their formation with that of the budding of zoospores from 

 the surface of the body in Noctiluca as described by Cienkowski*. 

 "We owe to Hertwig and Lesserf and to Franz Eil. SchulzeJ two 

 papers on Pseudochlamys patella (fig. 3), in which they supplement 

 and correct the description of this rhizopod as given by Claparede 

 and Lachmann. Its shell is of a brownish -yellow colour, shaped 

 like a watchglass, so as to be widely open on the inferior surface. 

 Here, according to Hertwig and Lesser, a delicate structureless 

 membrane stretches across the opening, which it closes, except in 



Fig. 3. 



Pseudochlamys fatella. 



Viewed from below, with opposite margins of the test 

 folded in, and with a protruded finger-shaped pseudo- 

 podium. 



(After F. E. Schulze.) 



a small central space which remains open for the passage of the 

 pseudopodia. Schulze, who makes no mention of this membrane, 

 describes indications of structure in the shell towards its summit 

 which recalls that of Arcella. 



The animal possesses the remarkable power of bringing into 

 juxtaposition the opposite margins of the wide shell-opening, thus 

 completely changing the form of the shell and making it resemble 

 the bivalve shell of a Lamellibranchiate mollusk or of a Oypris. 

 This approximation of the margins is evidently brought about by 

 the contractility of the contained protoplasm, while the return to 

 the previous condition would seem to result from the elasticity of 

 the shell. Schulze has noticed in some cases special bands of 

 protoplasm passing from the circumference of the body to the 

 margin of the shell to which they are attached. He believed they 

 act ill a way analogous to that of muscles in regulating the form 



of the orifice. 



The protoplasni-body is finely granular, and contains in ibs 

 periphery a great number of contractile vesicles, while there is a 



* Arch. f. ttiikr. Anat. vol. ix. p. 47. t Id. vol. x. Suppl. \ Id. vol. xi. 



